Get attachment

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description explains the two output modes and the size threshold, adding behavioral context beyond the readOnlyHint annotation. No contradiction with annotations; the tool is read-only and the description aligns.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with no wasted words. The main action and key conditions are front-loaded. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the core behavior (download modes, size threshold) and uses the schema well. However, it is slightly ambiguous whether savePath is always required for writing or only for large files. Overall, it is adequate given the tool's simplicity and rich schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already covers all parameters with descriptions (100% coverage). The tool description adds useful context: savePath is required for files >5MB, which is not in the schema. This enhances parameter understanding.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states 'Download one attachment from a message by index.' It specifies the verb (download), resource (attachment), and the two modes (base64 or file write) with a size threshold, distinguishing it from siblings like get_message.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context on when to use savePath (required for files >5MB) and otherwise returns base64. It does not explicitly compare with alternatives among siblings, but provides enough guidance for correct invocation.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.